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<html xmlns="http://www.w3.org/1999/xhtml"> 
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    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 
    <title>第七课 运算符</title>
</head> 
<body>
    <script>
        // var a = 3;
        // var b = -2;
        // alert(a > 0 && b > 0);
        // var a = 1;
        // var b = -3;
        // alert(a > 0 || b > 0);
        // var a = 1;
        // alert(!(a < 0));
        // var a = true;
        // alert(!!a);
        // var a = 1;
        // alert(a > 0 || a < -1);
        // alert(!a);
        // alert(Boolean(a));
        alert(true && 1 > 0 && !(2 < 1));
    </script>                     
</body> 
</html>